Subspecies

Genus

Species

subspecies

Region

Range

Nisaetus

bartelsi

OR

Java

Genus

Nisaetus is a genus of eagles found mainly in tropical Asia. They were earlier placed within the genus Spizaetus but molecular studies show that the Old World representatives were closer to the genus Ictinaetus than to the New World Spizaetus (in the stricter sense). They are slender bodied, medium sized hawk-eagles with rounded wings, long feathered legs, barred wings, crests and usually adapted to forest habitats

Range

Oriental Region : Java. Spizaetus bartelsi is endemic to the island of Java, Indonesia, where it is restricted to remaining patches of forest and is consequently scarce. An increase in survey effort and knowledge of the species’s home-range size has led to consecutive upward revisions of the global population, now estimated at over 600 individuals

Habitat

It frequents primary humid forest, although individuals and even nests have been recorded in secondary forest, production forest and tropical semi-deciduous forest. While it occurs from sealevel to high mountains, it is most frequent at 500-1,000 m.

Reproduction

Breeding generally takes place between January and July, although there are nesting records from all months. The nest is a large structure made of sticks and leaves, lined with green leaves, and placed in a large tree. Nest sites are usually in undisturbed forest, but at least one was in a tree plantation. The species becomes sexually mature at the age of three or four years, and pairs breed every two years, if they are successful. Some juveniles may stay in the vicinity of their nest until the following year. The clutch size is 1 egg. The incubation period is 47-48 days, and the nestling period is 70 days long. Both parents participate in feeding the young.

Feeding habits

Small mammals, including tree shrews, squirrels, bats, rats, and other small rodents are the preferred prey, but birds, snakes, and lizards are also taken. Prey is usually captured from a perch, but less commonly by soaring over the forest canopy and dropping on prey in a tree or on the ground.

Conservation

The population of this impressive raptor is very small. Moreover, given the destruction, disturbance and degradation that is currently being inflicted on its preferred habitat, it is likely to be declining and increasingly fragmented, a circumstance that qualifies it as Endangered.The key threats are habitat loss and trade. The burgeoning human population on Java brings with it intense pressure on natural resources, one aspect of which has been a massive reduction in forest cover, particularly in the lowlands. This threat continues in the form of conversion to agriculture, development and uncontrolled fire, even within protected areas. It is also sold openly in Javan bird markets, with 30-40 reported in trade each year, and presumably many more undetected. This threat appears to be intensifying, following the elevation of the species to national bird.